At our laboratory we have designed and completed a number of specialized monitoring systems, based on our platforms for WSN and a universal transport protocol built above ZigBee.
All systems contain the following common elements:
WZ coordinator is a central processing unit that controls the whole network and serves as a link to a PC. It collects data from all sensors of the network and controls actuators by means of unified profiles. Connection to the computer is made through USB interface (virtual serial port) and is only required at system startup to initialize control logic and algorithms from the high-level software. Power supply: 3V DC/6-12V AC.
WZ Router is used to build large spatially distributed networks. Its primary task is to transfer messages of other nodes and to find optimal routes subject to link quality. Compact size: 100x40x20 mm. Power supply: 3V DC/ 6-12V AC.
WZ Actuator controls high-voltage circuits through 4 independent channels.
WZ End Device contains a broad range of digital interfaces as well as analogue inputs for connection of external sensors.
All data transmitted over the wireless channel is secured with AES-encryption. Every transmission is acknowledged at the MAC layer (from the first neighbour node, which received the message) and at the transport layer (from the central network element).
A security monitoring system is a common example of WSN usage. It manages the following sensors and devices:
All information is processed at the network coordinator according to selected control profiles. Each profile contains descriptions of alarm conditions (e.g. no data from particular sensors, alarm signal from one or several devices) and actions to be taken in case of the triggered alarm (e.g. turn on siren, switch off light, send SMS message, etc). The profiles can be changed at the user PC.